The present invention generally relates to multiple laser beam positioning and energy deliver systems, and more particularly to laser micro-machining systems employed to form holes in electrical circuit substrates.
Various laser machining devices are used to micro-machine patterns in substrates. Such systems typically are used in the manufacture of electrical circuit boards. Electrical circuit board manufacture comprises depositing conductive elements, such as conductive lines and pads, on a non-conductive, typically dielectric, substrate. Several such substrates are adhered together to form an electrical circuit board. In order to provide electrical interconnection between the various layers of an electrical circuit board, holes, called vias, are drilled through selected substrate layers and plated with a conductor. Electrical circuit boards typically include tens of thousands of vias, and as many as several hundred thousand vias.
The present invention seeks to provide an improved laser micro-machining apparatus, such apparatus being particularly useful to form vias in electrical circuit boards.
The present invention still further seeks to provide an improved laser beam positioning system operative to provide generally simultaneous independent positioning of a plurality of laser beams.
The present invention still further seeks to provide laser micro-machining apparatus employing a laser beam positioning system operative to provide simultaneous independent positioning of a plurality of laser beams.
The present invention still further seeks to provide laser micro-machining system operative to independently position a plurality of pulsed laser beams, with a minimal loss in laser energy.
The present invention still further seeks to provide laser micro-machining apparatus that efficiently utilizes laser energy supplied by a pulsed laser, such as a solid state Q-switched laser, to generate vias in electrical circuit substrates.
The present invention still further seeks to provide laser micro-machining apparatus that controls an energy property of a laser beam by splitting an input laser beam into at least one output beams that are used to micro-machine a substrate. The at least one output beams may be a single beam or a plurality of beams.
The present invention still further seeks to provide a dynamic beam splitter operative to split an input laser beam into a selectable number of output sub-beams.
The present invention still further seeks to provide a dynamic beam splitter operative to selectably split an input laser beam into a plurality of sub-beams having a generally uniform energy property.
The present invention still further seeks to provide a system for selectably deflecting a pulsed beam to a selectably positionable beam reflector pre-positioned in an orientation to suitable for delivering energy to a selectably location on a substrate. Deflection of the beam may be performed at a duty cycle which is at least as fast as a pulse repetition of the laser beam. Positioning of the reflector is performed at a duty cycle which is slower than the pulse repetition rate.
The present invention still further seeks to provide a dynamic beam splitter operative to split an input laser beam into a plurality of output laser beams, each of which is directed in a selectable direction. In accordance with an embodiment of the invention, each of the output laser beams is emitted from a different spatial section of the beam splitter.
The present invention still further seeks to provide a laser beam diverter operative to receive a plurality of laser beams generally propagating in a common plane, and to divert each of the laser beams to a location in a two-dimensional array of locations outside the plane.
In accordance with a general aspect of an embodiment of the present invention, a laser beam positioning system, useful for example, to micro-machine substrates, is operative to provide a plurality of sub-beams which are dynamically deflected in a selectable direction. Each sub-beam is deflected so as to impinge on a deflector, located in an array of independently positionable deflector, whereat the sub-beams are further deflected by the deflectors to impinge on a substrate at a selectable location. In accordance with an embodiment of the invention, the plurality of sub-beams is generated from a single input beam by a dynamically controllable beam splitter.
In accordance with a general aspect of an embodiment of the invention, a system for delivering energy to a substrate, includes a dynamically directable source of radiant energy providing a plurality of beams of radiation, propagating in a dynamically selectable direction. Independently positionable beam steering elements in a plurality of beam steering elements are operative to receive the beams and direct them to selectable locations on the substrate.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of radiant energy providing a beam of radiation, a beam splitter operative to split the beam into a plurality of sub-beams, each sub-beam propagating in a selectable direction, and a plurality of independently positionable beam steering elements, some of which receive the plurality of sub-beams and direct them to selectable locations on the substrate.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of radiant energy providing a beam of radiation and a dynamically configurable beam splitter disposed between the source of radiant energy and the substrate.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of radiant energy providing a beam of radiation and an opto-electronic multiple beam generator disposed between the source of radiant energy and the substrate. The multiple beam generator is operative to generate at least two sub-beams from the beam and to select an energy density characteristic of each sub-beam.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of pulsed radiant energy providing a pulsed beam of radiation along an optical axis, the pulsed beam including multiple pulses separated by a temporal pulse separation, and a multiple beam, selectable and changeable angle output beam splitter disposed between the source of radiant energy and the substrate. The selectable and changeable angle output beam splitter is operative to output a plurality of sub-beams at a selected angle relative to the optical axis. The angle is changeable in an amount of time that is less than the temporal pulse separation.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of pulsed radiant energy providing a pulsed beam of radiation, the pulsed beam including multiple pulses separated by a temporal pulse separation, a beam splitter disposed between the source of radiant energy and a substrate, the beam splitter being operative to output a plurality of sub-beams at selectable angles which are changeable, and a plurality of selectable spatial orientation deflectors. The deflectors are operative to change a spatial orientation in an amount of time that is greater than the temporal pulse separation. Some of the spatial orientation deflectors are arranged to receive the sub-beams and to direct the sub-beams to the substrate.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of radiant energy providing a beam of radiation, a beam splitter operative to split the beam into a selectable number of output beams, the output beams having an energy property functionally related to the selectable number, a beam steering element receiving an output beam and directing the output beam to micro-machine a portion of a substrate.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of radiant energy providing a plurality of beams of radiation propagating in a plane and a plurality of deflectors receiving the plurality of beams and deflecting at least some of the beams to predetermined locations outside the plane.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one source of radiant energy providing a beam of radiation, a beam splitter operative to receive the beam and to output a plurality of sub-beams propagating in a plane, and a plurality of deflectors receiving the plurality of sub-beams and deflecting at least some of the plurality of sub-beams to predetermined locations outside the plane.
In accordance with another general aspect of an embodiment of the invention a method for delivering energy to a substrate comprises directing a first plurality of beams of radiation onto a first plurality of selectably positionable deflectors during a first time interval for directing the first plurality of beams onto a first plurality of locations, during the first time interval, selectably positioning a second plurality of selectably positionable deflectors, and during a second time interval, directing the first plurality of beams of radiation onto the second plurality of selectable positionable deflectors for directing the first plurality of beams onto a second plurality of locations.
In accordance with another general aspect of an embodiment of the invention a system for delivering energy to a substrate comprises at least one radiant beam source providing at least one beam of radiation and at least first and second deflectors disposed to receive the at least one beam to deliver the beam to respective at least first and second at least partially overlapping locations on the substrate.
In accordance with another general aspect of an embodiment of the invention a laser micro-machining apparatus includes at least one radiant beam source providing a plurality of radiation beams, a plurality of independently positionable deflectors disposed between the at least one radiant beam source and a substrate to be micro-machined, the plurality of independently positionable deflectors being operative to independently deliver the at least one radiation beam to selectable locations on the substrate, and a focusing lens disposed between the at least one radiant beam source and the substrate, the focusing lens receiving the plurality of radiation beams and being operative to simultaneously focus the beams onto the selectable locations on the substrate.
In accordance with another general aspect of an embodiment of the invention an acousto-optical device includes an optical element receiving a beam of radiation along an optical axis, and a transducer associated with the optical element, the transducer forming in the optical element an acoustic wave simultaneously having different acoustic frequencies, the optical element operative to output a plurality of sub-beams at different angles with respect to the optical axis.
In accordance with another general aspect of an embodiment of the invention a method for micro-machining a substrate includes providing a laser beam to a beam splitter device, splitting the laser beam into a first number of output beams and directing the first number of output beams to form at least one opening in a first layer of a multi-layered substrate, and then splitting the laser beam into a second number of output beams and directing ones of the second number of output beams to remove selected portions of a second layer of the multi-layered substrate via the at least one opening.
Additional features and aspects of the invention include various combinations of one or more of the following:
The source of radiant energy comprises a pulsed source of radiant energy outputting a plurality of beams each defined by pulses of radiant energy.
The pulsed source of radiant energy comprises at least one Q-switched laser.
A dynamically directable source of radiant energy comprises a beam splitter operative to receive a beam of radiant energy and splitting the beam into a selectable number of sub-beams.
A dynamically directable source of radiant energy comprises a beam splitter operative to receive a beam of radiant energy, to split the beam into a plurality of sub-beams and to direct the sub-beams each selectable directions.
The beam splitter comprises an acousto-optical deflector whose operation is governed by a control signal.
The beam splitter comprises an acousto-optical deflector having an acoustic wave generator controlled by a control signal, the acoustic wave generator generating an acoustic wave which determines the number of sub-beams output by the acousto-optical deflector.
The beam splitter comprises acousto-optical deflector having an acoustic wave generator controlled by a control signal, the acoustic wave generator generating an acoustic wave which determines the selectable directions of the sub-beams.
The acoustic wave in the acousto-optical deflector includes a plurality of spatially distinct acoustic wave segments, each spatially distinct acoustic wave segment being defined by a portion of the control signal having a distinct frequency.
Each spatially distinct acoustic wave segment in the acoustic wave determines a corresponding spatially distinct direction of a corresponding sub-beam, which is a function of the frequency of the portion of the control signal corresponding to the acoustic wave segment.
The number of spatially distinct acoustic wave segments determines the number of corresponding sub-beams.
The dynamically directable source of radiant energy comprises a dynamically configurable beam splitter receiving a beam of radiant energy and splitting the beam into a selectable number of sub-beams. The dynamically configurable beam splitter is capable of changing at least one of the number and direction of the sub-beams within a reconfiguration time duration, and the pulses of radiant energy are separated from each other in time by a time separation which is greater than the reconfiguration time duration.
The plurality of independently positionable beam steering elements is capable of changing the direction of the sub-beams within a redirection time duration, and the pulses of radiant energy are separated from each other in time by a time separation which is less than the redirection time duration.
Each of the beam steering elements includes a reflector mounted on at least one selectably tilting actuator. The actuator comprises a piezoelectric device or a MEMs device.
The number of beam steering devices exceeds the number of sub-beams included in the plurality of sub-beams. At least some of the plurality of sub-beams are directed to at least some of the plurality of beam steering devices while others of the plurality of the beam steering devices are being repositioned.
The selectable number of sub-beams all lie in a plane, a two dimensional array of beam steering elements lies outside the plane, and an array of fixed deflectors optically interposed between the at least one dynamically directable source of radiant energy and the plurality of independently positionable beam steering elements is operative direct the beams lying in a plane to locations outside the plane.